In are anucleate and normally homogeneous in appearance They have a biconcave shape with peripheral hemoglobinization and a central clear zone of pallor The biconcave cell shape allows for erythrocyt ID: 885534
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1 I n contrast to white blood cells, circ
I n contrast to white blood cells, circulating erythrocytes are anucleate and normally homogeneous in appear - ance. They have a biconcave shape with peripheral hemoglobinization and a central clear zone of pallor. The biconcave cell shape allows for erythrocyte movement through even the smallest capillaries , while hemoglobin carries oxygen fo
2 r delivery to tissues. Erythrocytes are
r delivery to tissues. Erythrocytes are derived from bone marrow ortho - chromic erythroblasts following extrusion of the nucleus. During development in the bone marrow, erythroid cells increase in RNA content for hemoglobin production; this RNA imparts a grayish color to the cell cytoplasm on - toplasmic color progressively becomes more orange-p
3 ink. Upon release into the circulation,
ink. Upon release into the circulation, erythrocytes are still slightly immature with slight grayish staining, a nding referred to as polychromasia. These polychromatophilic cells generally represent reticulocytes, although supravital or uorescent staining of RNA is required for con rmation. In normal patients, reticulocytes mature
4 within 1 or 2 days and only account fo
within 1 or 2 days and only account for about 1% of erythrocytes. Peripheral blood smear review, in conjunction with CBC, is quite useful in evaluating patients with erythrocyte disorders. In particular, erythrocyte staining characteris - tics (e.g., polychromasia or hypochromasia), erythrocyte shapes (e.g., schistocytes, spherocytes, bite cells
5 ), eryth - Parul Bhargava, MD Joan Etzel
), eryth - Parul Bhargava, MD Joan Etzell, MD William Finn, MD inclusions (e.g., Pappenheimer bodies, hemoglobin crys - tals), can assist in determining the underlying etiology. For example, in anemias due to bleeding or red cell de - struction (e.g., hemolysis), erythrocytes may be released early from the bone marrow, and polychromatophilic cells
6 since the bone marrow is properly compen
since the bone marrow is properly compensating for the anemia. Cell shapes assist in distinguishing etiologies for anemia; for example, schistocytes are in keeping with mi - croangiopathic hemolytic anemia, spherocytes are seen with autoimmune hemolytic anemia or hereditary sphero - cytosis, and bite cells may be seen with G-6-PD de ciency. -
7 rocyte destruction, lack of increased po
rocyte destruction, lack of increased polychromatophilic cells in an anemic patient suggests an underlying problem with erythrocyte production, as can be seen with nutri - tional de ciencies, bone marrow failure, or bone marrow replacement disorders. Red cell size is best assessed by an automated hema - tology analyzer, although in some cases s
8 mear review Erythrocytes - rocytes) ery
mear review Erythrocytes - rocytes) erythrocytes; normal erythrocytes are similar in size to small, mature lymphocytes. Microcytic anemia may be related to iron de ciency, heavy metal toxicity, or thalassemia, while macrocytic anemia may be the result of vitamin B12 or folate de ciency, liver disease, hypothy - roidism, or myelodysplasia.